Police arrested an 18-year-old wielding a machete with an 18-inch blade outside a polling station in Florida on Tuesday, who was part of a group of teenagers accused of intimidating Democratic supporters.

The teenager, Caleb James Williams, was arrested after 4 p.m. when officers were called to the Beaches Branch Library in Neptune Beach.

Williams was arrested on charges of aggravated assault for allegedly brandishing his weapon at two unidentified women, ages 71 and 54, and improper exhibition of a weapon, Neptune Beach Police Department said.

The local Democratic campaign said it was "deeply concerned" about the Tuesday's events, in which it said a group of young men waving signs supporting former President Donald Trump confronted a group holding signs promoting Kamala Harris.

Police Chief Michael J. Key Jr. told a news conference Tuesday night that officers found a group of eight, including seven juveniles and one adult, in the library's parking lot.

"The investigation revealed that the group arrived to protest and antagonize the opposing political side," he said.

The group approached opposing sign-wavers and an argument developed between the two sides, before Williams "brandished a machete in an aggressive, threatening posture over his head," Key said, adding that the department has released an image of this moment.

"The group was there for no other reason but for ill intentions, to cause a disturbance, " Key continued.

Key added that the incident was a clear case of actions going beyond what is allowed by free speech laws.

"This goes way beyond expressing freedom of speech — to say your piece is First Amendment-protected right but that goes out the window the moment you raise a machete over your head in a threatening manner," he said.

Key said there were no plans to arrest or charge any of the other members of the group as their actions didn't "cross the criminal threshold," but he stressed that an investigation is ongoing.

Duval County Democratic Party Chair, Daniel Henry commended the police for a swift response.

He said in a statement: "We are deeply concerned about a violent incident today at the Beaches Library, where a group of young men carrying Trump flags, with one individual armed with a machete, confronted peaceful Harris-Walz sign-wavers exercising their First Amendment rights."

Police have sought to assure people that the polling station and other sites in the county remain safe for voters.

Duval GOP did not immediately respond to an NBC News request for comment.